计及占空比限幅环节的直流配电系统暂态稳定性分析

Transient Stability Analysis of DC Distribution System Considering Duty Cycle Limiter

大功率扰动条件下,限幅环节容易造成占空比出现饱和现象,直流配电系统就会由闭环控制退化成开环响应并出现暂态失稳。为此,文中开展了计及占空比限幅环节的直流配电系统暂态稳定性分析。首先,文中利用Sigmoid函数模拟占空比限幅环节中的非线性特性,建立了更为贴近工程实际的直流配电系统大信号模型。其次,利用Takagi-Sugeno(TS)模糊模型法,刻画了计及占空比限幅环节影响的估计吸引域。然后,通过不同控制参数的估计吸引域变化情况,揭示了占空比饱和引发的直流配电系统暂态失稳现象。最后,针对占空比限幅环节导致已有暂态稳定性提升方法存在的局限性,提出了一种控制参数优化设计的方法,为提升系统暂态稳定性的控制参数选择提供了方案。RT-Box硬件在环实验验证了理论分析的有效性。

Under the condition of high power disturbance,the limiter is prone to the saturation phenomenon of duty cycle,and the DC power distribution system will be degraded from closed-loop control to open-loop response and transient instability.Therefore,this paper carries out the transient stability analysis of DC power distribution system considering the duty cycle limiter.Firstly,this paper uses Sigmoid function to simulate the nonlinear characteristics of duty cycle limiter,and establishes a large-signal model of DC distribution system which is closer to the engineering reality.Secondly,the estimated attraction domain taking into account the influence of the duty cycle limiter is characterized by the Takagi-Sugeno(TS)fuzzy modeling method.Then,the variation of the estimated attraction domain with different control parameters reveals the transient instability phenomenon of the DC distribution system induced by duty cycle saturation.Finally,for the limitations of the existing transient stability improvement methods due to the duty cycle limiter,an optimization design method of control parameters is proposed to provide a scheme for the control parameter selection to improve the transient stability of the system.The effectiveness of the theoretical analysis is verified by the RT-Box hardware-in-the-loop experiment.